<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <div id="app">
        <h2 v-show="age<18">you can see me now</h2>
        <button @click="change">click me to change below</button>
        <h2 v-show="isShow">you can see me now</h2>
    </div>

    <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
    <script>
        var app = new Vue({
            el:"#app",
            data:{
                message:"hello,black man",
                age:18,
                isShow:true,
            },
            methods: {
                change:function(){
                    this.isShow=!this.isShow;
                },
            },
        })
    </script>

</body>
</html>